Sharif Digital Repository

When a submarine pipeline is laid, pipeline spans may exist due to the unevenness of the seabed. Such pipeline spans when exposed to currents, may undergo vortex-induced vibration (VIV). As the flow velocity increases, the cross-flow oscillation begins to occur and vortex shedding frequency may approach the natural frequency of the pipe span. Amplified response due to resonance between the vortex shedding frequency of the free span may cause fatigue damage. Thus, the determination of the critical allowable span length under the various environments becomes the most challenging areas in the offshore industry. A substantial research effort related to various aspects of VIV and free span... 

Sour Gas is more dangerous than sweet gas because of its hydrogen sulfide contents. So it requires more safety considerations. In this project, the effect of wall thickness and design factor of pipeline on the safe distance was examined by using risk assessment method. The safe distance tables for 4 pipelines with different wall thicknesses and design factors were prepared based on operating pressure, pipe diameter and hydrogen sulfide concentration in gas by using PHAST and PHAST RISK softwares. In this project, the depth of cover parameter was considered in safe distance determination. Also the leak of sour gas was simulated by using... 

Pipelines are the preferred means for transporting of liquid or gas phase materials. The economy of many countries is extremely dependent upon a large network of pipelines systems to transport and distribute the nation’s energy resources. Damages to the pipe structure may cause leakage and result in economic losses or even loss of life. Developing methods for detecting the anomalies and damages to the structure before they lead to catastrophic events is vital. Multiple pipeline misadventures over the past several years have resulted in hundreds of fatalities and billions of dollars in property damages. These accidents demonstrate that the current monitoring methods are not sufficient... 

Sudden pressure drop and then the gas shortage in city gas stations is one of the most important problems in high-pressure natural gas transmission networks. On the other hand, power consumption of compressors imposes a lot of cost on compressor stations. The conventional schemes to navigate the compressor stations are traditional methods based on experiment and trial and error which cause energy waste and violation of the optimal operating conditions. In this research, two manners of centralized- and decentralized- control are employed in order to navigate compressor stations in specified operating conditions regarding the operational and practical constraints. In this purpose, a sample gas... 

Structural Health Monitoring (SHM) of pipelines is an important task for economic/safety reasons which depends on the method of study of the integrity profile of the pipeline structure. Process pipes, particularly, pipelines in thermal power plants are susceptible to stress corrosion cracking (SCC). Failure of these pipes may result in catastrophic damages, thus, require systematic regular inspections. The damage assessment may demand embedding of appropriate sensors and specific data analysis techniques. According to what is reported from the respective experiments, data analysis of a single sensor may not be adequate to provide a reasonable damage assessment, and in turn to making a... 

Structural Health Monitoring (SHM) means to give a diagnosis of the “state” of the subjects. Small leaks along the entire lengths of oil pipelines are detected and located by monitoring.Nowadays health monitoring of pipeline in water, gas, oil and chemical industry has been the focus of researchers. This is due to the fact that leak accidents may cause great economic problems to human resources as well as extreme environmental pollution. This project focuses on a visual and photographic observation system as leakage detection to monitor long range pipelines. In this system, several cameras with overlapping views are located along the entire lengths of pipelines. We are using digital cameras... 

Pipeline systems have a major role in civil infrastructure for transportation of energy sources including, petroleum, natural gas, and water. As most pipelines are located in hard-access location such as underground and sea as well as mountains, they are vulnerable to corrosion, cracks and thus, unpredictable failure. Failure of pipelines not only costs millions of dollars but also causes environmental damage, requiring continuous health monitoring systems to provide early detection and early warning of flaws such as corrosion and leaks. Structural health monitoring based on ultrasonic guided waves is used in structures as plates, composites, rods, piping and tubing. This research aims to... 

In this study, the seismic response analysis of a buried pipeline had been performed using three-dimensional (3D) dynamic analysis of the soil-pipeline interaction under different loading inputs. A number of parameters such as properties of the buried pipeline including diameter and internal pressure and different loading frequencies were used for this investigation. The pipe was considered as an elastoplastic material and a nonlinear elastic material based on the Mohr–Coulomb criterion was used to model the soil behavior. In addition, pipe-soil interaction has been studied in both tangential and vertical directions. The ABAQUS software was utilized for the 3D numerical modeling and... 

Analog to digital converters with different specifications are widely used in modern electronic circuits. The significant demand on pipeline converters in several low power applications is mainly due to their high speed and high resolution characteristics. Fast and simple design of analog circuits using CAD tools, is highly sought after by integrated circuit designers. In this thesis, pipeline analog to digital converters is studied and a CAD tool is proposed for transistor level design and optimizations. The main advantage of this design in comparison with the previous works is that the yield and power consumption are considered as optimization factors. The module operates in three parts:... 

The set processes of carbon dioxide capture, transfer and storage in underground water source, called CCS. Carbon dioxide capture and storage is a process consisting of the separation of carbon dioxide from industrial and energy-related sources, transport to a storage location and long-term isolation from the atmosphere. Carbon dioxide is the most important greenhouse gases, which causes global average temperature rise and controller institutions want the companies and refineries to follow this issue.Under normal circumstances, there is minor amounts of carbon dioxide gas in the air which its concentration is close to 0.04 percent. The concentration of between 7 to 10 percent is a serious... 

Although using cathodic protection in addition to coating with paint will extend the life of pipelines drastically, it can also accelerate disbondment of coating at coating defects. In this research four usual pipeline coating systems have been examined from applicational aspects and the best coating system among them has been introduced. The four coating systems were consisted of: epoxy coal tar 212 with epoxy 155 primer, solvent free polyamine epoxy 474HG without primer, glasscote 440 witout primer and glasscote 440 with epoxy 155 primer. According to ASTM G8, cathodic disbondment test was accomplished for eight samples simultaneously. During the tests cathodic protection current and... 

This research evaluates the effect of external corrosion geometry and bending moment on the burst pressure of pipes. In recent decades, the use of natural resources of offshore oil and gas has increased, as a result, the use of offshore pipelines for transferring products has grown dramatically. At the same time, numerous accidents and explosions in offshore pipelines and its economic and environmental consequences indicates the importance of ensuring safe operation. Pipeline Integrity Management has been developed to ensure safe and efficient operation of pipelines. Integrity management includes planning, inspection, evaluation and repair. This cycle is checked continuously. The importance...